Board Foot Calculator

A board foot is 144 cubic inches of lumber: a piece 1 inch thick, 12 inches wide and 12 inches long. It is a unit of volume, so it lets you compare two boards of completely different sections on the same footing.

The formula follows directly from the definition. With the length in inches it is thickness x width x length divided by 144. With the length in feet it is thickness x width x length divided by 12. Thickness and width are in inches in both versions.

Multiply thickness in inches x width in inches x length in inches, then divide by 144. A 2x6 that is 8 ft long is 96 inches long, so 2 x 6 x 96 / 144 = 8 board feet.

If the length is already in feet, divide by 12 instead: 2 x 6 x 8 / 12 = 8. Same answer, one less conversion. A 1 x 12 board 10 ft long is 1 x 12 x 10 / 12 = 10 board feet. Multiply by the number of identical boards at the end, never in the middle.

No. A surfaced dry 2x4 measures 1 1/2 by 3 1/2 inches. The nominal name comes from the rough green size the board was sawn at, and it stays with the piece after drying and surfacing take it down to the finished size.

The pattern in the American Softwood Lumber Standard is easy to remember: below 8 inches nominal, subtract 1/2 inch, so a 2x6 is 1 1/2 x 5 1/2. At 8 inches and above, subtract 3/4 inch, so a 2x8 is 1 1/2 x 7 1/4. Nominal 1 inch thickness finishes at 3/4 inch. Green lumber runs slightly larger because it will shrink, and rough sawn stock is full size or close to it.

Nominal for pricing, actual for the wood itself. Softwood board footage is conventionally figured on nominal size, so a 2x6 at 8 ft counts as 8 board feet even though it holds 5.5 board feet of real wood. Every supplier prices with that convention already built in, so switching to actual dimensions does not save you money, it just makes your number disagree with theirs.

Use the actual measured size when the question is about the wood rather than the bill: how much a load weighs, how much finish it will take, or whether a piece will fit a pocket. This page shows both at once, so you never have to guess which number a quote is based on.

It is the same thickness expressed the way hardwood yards write it. 4/4 is four quarter inches, so one inch. 5/4 is 1 1/4, 6/4 is 1 1/2 and 8/4 is 2 inches. The convention exists because hardwood is sawn in quarter inch steps rather than to a set of named sizes like 2x4.

The catch is that the number refers to the rough thickness before surfacing. Buy 4/4 stock surfaced on both faces and it commonly measures about 13/16 in when it reaches you, but it is still sold and figured as 1 inch. That is normal and it is not a shortfall, but it does mean you cannot plan a 1 inch thick finished part out of 4/4 surfaced stock. Order 5/4 for that.

It depends entirely on what you are buying. Pulling exact lengths off a store rack, the answer can be zero, which is why this calculator starts there rather than quietly padding your number.

Buying rough hardwood is a different job. You lose material jointing one face, planing to thickness, ripping a straight edge, cutting around knots and checks, and again if you are matching grain across a panel. Woodworkers commonly add somewhere between 15% and 30% for that, and the honest answer is that the right figure depends on the grade you buy, the defects in the specific boards and how fussy you are. Set your own number in the allowance box, and note that the allowance is always shown on its own line here so you can see exactly what was added.

A linear foot is simply a foot of length, ignoring the section. Ten linear feet of 1x4 and ten linear feet of 2x12 are the same length and wildly different amounts of wood.

A board foot is a volume, so it accounts for thickness and width as well. That 10 ft of 1x4 is 3.33 board feet, while 10 ft of 2x12 is 20 board feet, six times more wood. Trim, molding and decking are often priced per linear foot because the section is fixed; rough lumber is priced per board foot because it is not.

Yes. Use the Cut List mode. Enter a board, set its quantity, give it a label if you like, and press Add To Cut List. Repeat for every different size in the project and the grand total board footage and cost update as you go.

Each line keeps its own dimensions so you can check the arithmetic afterwards, and the materials ticket prints the whole list. Everything stays in your browser and nothing is sent anywhere.